Histoplasmosis is a fungal infection caused by Histoplasma capsulatum. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; called disseminated histoplasmosis, it can be fatal if left untreated.
Histoplasmosis is common among AIDS patients because of their suppressed immunity. In immunocompetent individuals, past infection results in partial protection against ill effects if reinfected.
Histoplasma capsulatum is found in soil, often associated with decaying bat guano or bird droppings. Disruption of soil from excavation or construction can release infectious elements that are inhaled and settle into the lung.
From 1938 to 2013 in the US, 105 outbreaks were reported in a total of 26 states plus Puerto Rico. In 1978 to 1979 during a large urban outbreak in which 100,000 people were exposed to the fungus in Indianapolis, victims had pericarditis, rheumatological syndromes, esophageal and vocal cord ulcers, parotitis, adrenal insufficiency, uveitis, fibrosing mediastinitis, interstitial nephritis, intestinal lymphangiectasia, and epididymitis. Histoplasmosis mimics colds, pneumonia, and the flu, and can be shed by bats in their feces.